Regular-Expressions

代码说明：

  正则表达式（regular expression）就是用一个“字符串”来描述一个特征，然后去验证另一个“字符串”是否符合这个特征。比如 表达式“ab+” 描述的特征是“一个 a 和 任意个 b ”，那么 ab , abb , abbbbbbbbbb 都符合这个特征。(Regex (regular expression) is to use a " string" to describe a feature , and then to validate another " string" whether this feature . For example the expression "ab+" features described "a a and any number of b ", then the ab , abb , abbbbbbbbbb are in line with this feature .)